The agency said the banks' global push won't affect their ratings over the next two to three years, though some lenders' profitability might be hurt in the domestic market due to escalating competition.

Generally, aggressive overseas expansion increases a bank's risk exposure by subjecting it to swings in the overseas market, though it will benefit in the long run.

The agency sees it as "an unlikely scenario" that Chinese banks will be substantially affected by overseas markets.

Part of the reason is that Chinese banks mostly expand through organic growth rather than acquisitions and, despite their fast growth, their overseas assets remains low as a percentage of their total assets, at below 10 percent.

Chinese banks currently have 1,148 overseas branches in Asia, Europe, the Middle East and the Americas, up 29 percent from 2010.

Their overseas assets have also increased rapidly. Industrial and Commercial Bank of China, the nation's biggest lender, has seen its offshore assets increase at an average annual rate of 39 percent since 2010.

Jin Lin, a banking industry analyst with Orient Securities Co Ltd, said that Chinese banks' global push, at its

current stage, is unlikely to damage their balance sheets.

"The expansion is fast but also with a measure of prudence. I don't think their overseas operations could damage their overall profitability," said Jin.